Have your tried playing music through the DVD drive? I know this sounds a odd question but you can get so much music on a DVD than cd! Do you have bluetooth?
I haven't tried - that would mean losing the nav.
Yep - bluetooth is in, however the iPhone 4 integration appears to be limited to it fitting neatly in the compartment to the lower right of the steering wheel, where it can be put out of sight and not worry the car that its technology is a good 10 years behind.
Do you not have a arm rest cradle for it?
Yeah - no iPhone specific connection though. I just use the aux cable and then change music on the phone. Tried once to connect the phone to the car with bluetooth, failed, liked the car a little less and never tried again.